Thermal Analysis of a Novel Compact Packaged Passively Cooled Laser Diode Array

The temperature of a laser diode array chip must be maintained under a safe level during operation in order to achieve satisfactory performance and lifetime. In this paper, 3-D thermal analysis on diode heatsink is presented. The boundary condition at the bottom of heatsink is constant convective heat transfer coefficient. In addition, heat transfer in thermal-entry region of tubes is accounted for to calculate the convective heat transfer coefficient. Moreover, a 12 mm times 37 mm times 7 mm passively cooled laser diode array cooled by a base heatsink is demonstrated. Up to 62 W output power with an electrical-to-optical conversion efficiency of 49.2% are achieved. System thermal resistance of 0.77 K/W is obtained when the flow rate through the base heatsink with 0.8-mm-wide, 2-mm-high and 20-mm-long channels is 25 cm³/s.